On Graphs with Proper Connection Number 2

An edge-colored graph is properly connected if for every pair of vertices u and v there exists a properly colored uv-path (i.e. a uv-path in which no two consecutive edges have the same color). The proper connection number of a connected graph G, denoted pc(G), is the smallest number of colors neede...

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Autores principales: Jill Faudree, Leah Berman, Glenn Chappell, Chris Hartman, John Gimbel, Gordon Williams
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Lenguaje:EN
Publicado: Georgia Southern University 2021
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Acceso en línea:https://doaj.org/article/5564ffd186f04c75936316bb80f35082
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spelling oai:doaj.org-article:5564ffd186f04c75936316bb80f350822021-11-16T16:59:16ZOn Graphs with Proper Connection Number 22470-985910.20429/tag.2021.080202https://doaj.org/article/5564ffd186f04c75936316bb80f350822021-08-01T00:00:00Zhttps://digitalcommons.georgiasouthern.edu/tag/vol8/iss2/2https://doaj.org/toc/2470-9859An edge-colored graph is properly connected if for every pair of vertices u and v there exists a properly colored uv-path (i.e. a uv-path in which no two consecutive edges have the same color). The proper connection number of a connected graph G, denoted pc(G), is the smallest number of colors needed to color the edges of G such that the resulting colored graph is properly connected. An edge-colored graph is flexibly connected if for every pair of vertices u and v there exist two properly colored paths between them, say P and Q, such that the first edges of P and Q have different colors and the last edges of P and Q have different colors. The flexible connection number of a connected graph G, denoted fpc(G), is the smallest number of colors needed to color the edges of G such that the resulting colored graph is flexibly connected. In this paper, we demonstrate several methods for constructing graphs with pc(G) = 2 and fpc(G) = 2. We describe several families of graphs such that pc(G) ≥ 2 and we settle a conjecture from [BFG+12]. We prove that if G is connected and bipartite, then pc(G) = 2 is equivalent to being 2-edge-connected and fpc(G) = 2 is equivalent to the existence of a path through all cut-edges. Finally, it is proved that every connected, k-regular, Class 1 graph has flexible connection number 2.Jill FaudreeLeah BermanGlenn ChappellChris HartmanJohn GimbelGordon WilliamsGeorgia Southern Universityarticleproper connectionedge-coloringclass 1 graphsMathematicsQA1-939ENTheory and Applications of Graphs, Vol 8, Iss 2 (2021)
institution DOAJ
collection DOAJ
language EN
topic proper connection
edge-coloring
class 1 graphs
Mathematics
QA1-939
spellingShingle proper connection
edge-coloring
class 1 graphs
Mathematics
QA1-939
Jill Faudree
Leah Berman
Glenn Chappell
Chris Hartman
John Gimbel
Gordon Williams
On Graphs with Proper Connection Number 2
description An edge-colored graph is properly connected if for every pair of vertices u and v there exists a properly colored uv-path (i.e. a uv-path in which no two consecutive edges have the same color). The proper connection number of a connected graph G, denoted pc(G), is the smallest number of colors needed to color the edges of G such that the resulting colored graph is properly connected. An edge-colored graph is flexibly connected if for every pair of vertices u and v there exist two properly colored paths between them, say P and Q, such that the first edges of P and Q have different colors and the last edges of P and Q have different colors. The flexible connection number of a connected graph G, denoted fpc(G), is the smallest number of colors needed to color the edges of G such that the resulting colored graph is flexibly connected. In this paper, we demonstrate several methods for constructing graphs with pc(G) = 2 and fpc(G) = 2. We describe several families of graphs such that pc(G) ≥ 2 and we settle a conjecture from [BFG+12]. We prove that if G is connected and bipartite, then pc(G) = 2 is equivalent to being 2-edge-connected and fpc(G) = 2 is equivalent to the existence of a path through all cut-edges. Finally, it is proved that every connected, k-regular, Class 1 graph has flexible connection number 2.
format article
author Jill Faudree
Leah Berman
Glenn Chappell
Chris Hartman
John Gimbel
Gordon Williams
author_facet Jill Faudree
Leah Berman
Glenn Chappell
Chris Hartman
John Gimbel
Gordon Williams
author_sort Jill Faudree
title On Graphs with Proper Connection Number 2
title_short On Graphs with Proper Connection Number 2
title_full On Graphs with Proper Connection Number 2
title_fullStr On Graphs with Proper Connection Number 2
title_full_unstemmed On Graphs with Proper Connection Number 2
title_sort on graphs with proper connection number 2
publisher Georgia Southern University
publishDate 2021
url https://doaj.org/article/5564ffd186f04c75936316bb80f35082
work_keys_str_mv AT jillfaudree ongraphswithproperconnectionnumber2
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AT glennchappell ongraphswithproperconnectionnumber2
AT chrishartman ongraphswithproperconnectionnumber2
AT johngimbel ongraphswithproperconnectionnumber2
AT gordonwilliams ongraphswithproperconnectionnumber2
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